The present invention relates to an image output apparatus such as a printer connected to a host computer or the like and a control method for the apparatus.
Conventionally, an image output apparatus such as a well-known laser-beam printer is connected to a host computer with a standard interface cable. When image data described in PDL (Page Description Language) is inputted from the host computer, the image data is interpreted and bitmap data is generated. Then, to output the data to a printer engine, the bitmap data is converted into a binary signal, thus hard copy output is produced from the printer.
The printer engine of this laser-beam printer transfers an image formed with print material called toner based on the binary signal onto a print medium, and fixes the transferred image onto the print medium by a fixer having fixing rollers and a fixing heater.
In recent years, it has been a trend to provide printers with an increased printing speed and energy-saving and low-cost structure.
However, a general laser-beam printer has a problem of fixing failure such as fixing offset in the fixer. The fixing offset means attachment of toner via a pair of fixing rollers to print sheets. Specifically, upon fixing processing, if toner is attached to the print-surface side roller, the toner is attached to the rear-surface side fixing roller, and is attached to the subsequent pages of print sheets. Especially, in a high-speed printer, the fixing failure such as fixing offset tends to be noticeable when printing has been performed to a certain extent. To address the problem, a special cleaning mechanism may be provided, however, in consideration of recent energy-saving and low-price requirements, such additional mechanism should be omitted as much as possible.
Accordingly, as countermeasures against the fixing failure without cleaning mechanism, a user manually cleans the fixer, or periodically inserts cleaning paper into the fixer.
As described above, it is preferable to clean the fixer every predetermined number of print sheets, however, in a case where the special cleaning mechanism is provided, the cost increases for the mechanism, and in a case where the user""s operation is required, the user must be aware of periodical cleaning operation and the user might forget it, further, the user must do it at much expense in time and effort.
The present invention has been made in consideration of the above problems, and has its object to prevent quality degradation due to fixing failure such as fixing offset or the like at a low cost.
According to the present invention, the foregoing object is attained by providing an image output apparatus comprising: transfer means for transferring a toner image generated based on image information onto a print sheet; fixing means, having a fixing roller, for fixing the toner image transferred onto the print sheet to the print sheet; and rotation control means for rotating the fixing roller for a predetermined period at timing other than that of fixing operation.
Preferably, the image output apparatus further comprises detection means for detecting whether or not a predetermined number of pages have been discharged, wherein if the detection means detects that the predetermined number of pages have been discharged, the rotation control means rotates the fixing roller for the predetermined period after page discharge.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same name or similar parts throughout the figures thereof.